Nucleic acid sequencing has become one of the main analytical techniques of modern molecular biology. The development of reliable methods for sequencing has advanced the understanding of the organization of genetic information and has made possible the manipulations of genetic material (i.e., genetic engineering). There are a variety of methods for sequencing nucleic acid molecules. Historically, the most common methods have been based on chemical (Maxam and Gilbert sequencing) or enzymatic (Sanger dideoxy sequencing and exonuclease-based sequencing) reactions that create specific truncated nucleic acid molecules that are then separated by electrophoretic techniques in order to determine their relative length. More recently, potentially higher throughput techniques, including pyro-sequencing, nanopore sequencing technology, hybridization-based sequencing methods, and the use of non-radiation based technologies for visualization of sequencing results, have been developed. It also has been proposed that scanning tunneling microscopy could be used to directly visualize the sequence of a nucleic acid molecule.
Additionally, a variety of nucleic acid detection techniques, including polymerase chain reaction (PCR), ligase chain reaction (LCR), nucleic acid sequence based amplification, strand displacement amplification, amplification with Q replicase, and numerous hybridization techniques, are utilized to detect the presence of nucleic acids of varying abundance from a variety of sources. Some strategies combine nucleic acid detection techniques with nucleic acid sequencing methods.